1. Field
The following description relates to an optimal transmission power technology, and more particularly, to a technology to determine an optimal user schedule and an optimal transmission power of each cell in a hierarchical-cell communication system or a multi-cell communication system.
2. Description of Related Art
Studies on a hierarchical-cell communication system or a multi-cell communication system including a plurality of cells are currently being conducted to improve the data transmission rate and the reliability of communication while at the same time using limited radio resources. For example, the plurality of cells may include a cellular base station, a femto base station, a fixed base station, a mobile base station, a relay station, terminals, and the like.
For example, each of a plurality of base stations in a plurality of cells may simultaneously use limited radio resources, such as, frequency, time, code resources, and the like, to improve efficiency in using the radio resource and to communicate with corresponding terminals. Also, when the plurality of base stations simultaneously use the limited radio resources, various difficulties occur, such as interference occurring in between the terminals that causes a decrease of a throughput to and from the terminals.
A dynamic spectrum management (DSM) scheme is proposed to solve the difficulties caused by the interference. According to the DSM scheme, each of the plurality of base stations may dynamically adjust spectrum power to decrease the interference received by other cells. In this example, determining of optimal transmission powers is important to decrease the interference.
In addition, each of the plurality of cells may perform user scheduling to serve multi-users. A result of the user scheduling may affect the throughput of the hierarchical-cell communication system or the multi-cell communication. Thus, there is a desire to consider user scheduling when determining the optimal transmission powers and/or to consider the transmission powers to determine an optimal user scheduling.